The present invention relates generally to optical network systems, and more particularly to a system and method for integrating optical crossconnect functionality in an optical packet switching apparatus.
Data traffic over networks, particularly the internet, has increased dramatically over the past several years, and this trend will continue with the introduction of new services which require more bandwidth. Over time and technological advancements the bandwidth bottleneck kept shifting between the transmission and switching. Now transmission technology has advanced to a level that the routers, which essentially switch packets, have become bottlenecks. The advance of Wavelength Division Multiplexing (WDM) has enabled overcome this transmission bottleneck. The enlarged volume of internet traffic requires a network with high transmission capacity and high capacity routers capable of routing data packets at a very high rate. One option is to use all-optical routers.
Advances in optical component technology had made it possible to make optical switching elements such as a Semiconductor Optical Amplifier (SOA) that would be electrically controlled to switch at nano-second response range. So a switching matrix made of a number of SOAs and controlled by routing protocols and a resource management software or hardware will enable all optical routers to act as a synchronous or asynchronous fixed or variable length packet switching apparatus.
One approach called burst switching attempts to make the best use of optical switching and electronic/software router technologies. It becomes feasible to implement an all-optical packet switching apparatus using burst switching technique. It creates a burst switched network with conventional packet switching devices such as routers with a special function at the ingress and egress points (edge) of this burst switched network. The special function to be performed by the edge packet switching devices would be assembly of multiple packets into one payload and send it into the burst switching network as a burst. Similarly they would unassemble packets in an incoming burst payload and send them as conventional packets outside of the burst switched network. When it is in the process of assembling bursts into a payload it would already have sent a header to the appropriate all-optical packet switch through which all the packets assembled into the payload has to pass through. The header would contain information about the contents, the arrival port and the destination port(s), the length of the burst payload etc. The all-optical packet switching device would receive this header and process it electronically and keep the switching matrix ready for an interval of time to allow the corresponding payload that would follow later at a known time instance to switch over to the right exit port.
Optical crossconnects on the other hand are not restricted to packets. They are devices that just make interconnections between an input port and output port to facilitate the establishment of light paths between devices connected to these two ports. They do not examine the packets that pass through them nor do they switch individual packets. Optical crossconnects are primarily used to establish steady optical paths between two circuit switching or packet switching devices. They also use a optical switching matrix to establish this connectivity. Currently, optical packet switching devices and optical crossconnects are two physically separate systems having separate switching hardware and software with possible interoperable ports for interconnection.
The present invention provides an optical network that substantially eliminates or reduces disadvantages and problems associated with previously developed optical networks used for switching data.
More specifically, the present invention provides a method for integrating optical crossconnect functionality in an optical packet switching apparatus. To integrate optical crossconnect functionality in an optical packet switching apparatus, a network manager begins by transmitting a request to a resource management mechanism for allocation for an output port with respect to an input port in an optical switching matrix. The resource management mechanism then queries a port availability database to determine the availability of the requested output port. If an output port is available, the resource management mechanism then reserves the requested output port. The resource management mechanism then transmits mapping information for an optical path between the input port and the reserved output port to an optical switch control mechanism. The optical switch control mechanism then creates the optical path between the said input port the reserved output port. Next, the optical switch control mechanism then informs the resource management mechanism that the optical path is established.
The present invention provides an important technical advantage by providing a method for integrating optical crossconnect and packet switching functionality in a single optical packet switching apparatus, thus reducing the number of components and cost.
The present invention provides another technical advantage by providing an optical packet switching apparatus with optical crossconnect function which works for any fixed length, variable length, synchronous, or asynchronous optical packet.